Set a new track record @ VIR this weekend...

[Cobra4B]

Got very lucky with the weather... it didn't rain at all on Saturday, poured that night, then stopped misting by 8:30 on Sunday and the track began to dry. The forecast all week was showing a potential washout.

Ended up setting a new VIR track record for my class (TimeTrials TTA) with a 2:04.6 on Saturday. The previous record of 2:04.8 was set in February by a fellow competitor in his Subaru STI.. Prior to that the record was held by a gentleman from Georgia (Mark Nunnally) in a TTA Z06 with a 2:05.3. At these speeds every little bit counts. My previous personal best was a 2:05.59 which I set in February so I ended up taking a second off my time. I ended up winning my class again on Sunday with a 2:05.1 on a drying track.

Only downer of the weekend was when my student and I (him driving) ran over a dog on track I've seen deer get hit, but never a dog on track. Luckily it wasn't someone's at the track, but was a "wild" Danville dog. We were going over 100 in the uphill esses so nothing we could do to avoid it.

Here's a few pics from Finishline Production showing the NASCAR-style spoiler and the 255 tires...

255s doing work....


NASCAR WOOOO!!!!!


It's ok if the wheel touches the track right?


Looks like a dragstrip launch


More pics here - http://www.finishlineprod.net/nasa/index.htm
(scroll down to the NASA Mid-Atlantic VIR March Madness Pictures area.

Here's my 2:04.6 record lap, but held up by Greg Zimpel's C6 Z06 as viewed from Barry Battle driving a GTS3 M3 to it's fastest lap ever 2:03.7 (it's Kyle Bacon's car)

http://vimeo.com/21612824

Here's my in-car

http://www.youtube.com/watch?v=jyAIEvWyQgo

Chasing a buddy in the first timed session Saturday... he had a little off, but controlled it nicely

http://www.youtube.com/watch?v=aWSTjaO0gdE

-Brian

[NZGTRA17]

Nice work Brian.

As I had hoped the spoiler looks better in action!! Seems to be working for you as well. Always a little hard to know though where the improvement comes from, track time or changes to the car. Did you try taking the spoiler off and running some times?

Kel.

[Cobra4B]

Originally Posted by NZGTRA17

Nice work Brian.

As I had hoped the spoiler looks better in action!! Seems to be working for you as well. Always a little hard to know though where the improvement comes from, track time or changes to the car. Did you try taking the spoiler off and running some times?

Kel.

Yes it's hard to know if it was the cold air making more power, me being more comfortable with the car, etc. etc. etc.

At Road Atlanta I ran scrub 275s w/o the spoiler on Saturday then brand new 255s with on Sunday. I was faster on Saturday, but I think that was due to the track just being slow on Sunday as it was a good bit hotter. The car felt faster, but it never showed up on the clock.

For this weekend at VIR I just ran it with the 255s and spoiler the whole time. Comparing to my older traqmate data w/o the spoiler and running the 275 tires I'm faster in some of the high-speed stuff, but more interestingly are the few areas I don't slow down as much. Also my braking performance at the end of the two straighs is substantially improved since the car is so much more stable now.

The ideal would be brand new 275s w/o spoiler and brand new 255s w/ spoiler all in the same day to test... however that's just not feasible for me. I took a gamble running the 255s (nobody has done that yet in my class) to free up mod points to run the spoiler. The gamble paid off w/ a new track record for the class so that's proof enough for me. Had the car been a bear to drive and slowed down then the spoiler would have gone back on the shelf until I moved to a class where I could run it with larger tires.

The concern was if the car would be able to put the power down coming out of turns... I had 100% zero issues. The only issue I did have was increased lower-speed understeer. At first I thought it was the spoiler causing the front to be light, but after more thought I really thing the super low sidewall of the 255/35 is just so stiff that it increases the effect of the front swaybar. My front bar is a GM racing T1 (SCCA class) bar and it's not adjustable. If it was I'd have tired softening it up a little. My rear bar is 3-way adjustable but it's currently on full-soft. I didn't want to stiffen it up for fear of making the car tail-happy especially with the tiny rear tires.

-Brian

[NZGTRA17]

Originally Posted by Cobra4B

The concern was if the car would be able to put the power down coming out of turns... I had 100% zero issues. The only issue I did have was increased lower-speed understeer. At first I thought it was the spoiler causing the front to be light, but after more thought I really thing the super low sidewall of the 255/35 is just so stiff that it increases the effect of the front swaybar. My front bar is a GM racing T1 (SCCA class) bar and it's not adjustable. If it was I'd have tired softening it up a little. My rear bar is 3-way adjustable but it's currently on full-soft. I didn't want to stiffen it up for fear of making the car tail-happy especially with the tiny rear tires.
-Brian

Brian, are the front shocks in your car adjustable? Did you try playing with tyre pressures to impact the understeer?

Kel.

[Cobra4B]

Originally Posted by NZGTRA17

Brian, are the front shocks in your car adjustable? Did you try playing with tyre pressures to impact the understeer?

Kel.

No I have to run stock 2004 Z06 shocks so there's nothing to change. I didn't lower tire pressures anymore because the outer edge of the tire was already getting a serious workout. The LF tire gets beat up at VIR... I almost corded it after Saturday's runs. I put 3 heat cycles on it and they had 4 on them from Road Atlanta.

I started them at 25 front and 24 rear cold. I like them in the 32-33 range hot.

[Squerly]

Originally Posted by Cobra4B

Only downer of the weekend was when my student and I (him driving) ran over a dog on track

Is the dog OK?

[Cobra4B]

Originally Posted by Squerly

Is the dog OK?

Never had a chance.... dead on impact.

[NZGTRA17]

Originally Posted by Cobra4B

No I have to run stock 2004 Z06 shocks so there's nothing to change. I didn't lower tire pressures anymore because the outer edge of the tire was already getting a serious workout. The LF tire gets beat up at VIR... I almost corded it after Saturday's runs. I put 3 heat cycles on it and they had 4 on them from Road Atlanta.

I started them at 25 front and 24 rear cold. I like them in the 32-33 range hot.

Brian, have you used a pyrometer to measure temps across the tyre to check that you are running optimum camber and pressure? While the cold/hot pressures are not to far off what we seek to run (we look for a slightly lower hot pressure 31 - 32) the cording issue combined with the handling suggests some adjustment may help. I think I would also have tried barring up slightly in the rear to help the front out.

Kel.

[Cobra4B]

I don't own a pyrometer yet. Plus, my camber is fixed in place with solid blocks so I can't change it unless I put a new block in. I can decrease it by shimming out the upper A-arm though. Right now I'm running 2.7 in th LF and about 2.6 in the RF as of my last allignment.

I'm not sure more camber will help... I think it's a function of running a 255/35 tire on a 10.5" wheel with a 2900lb car on top of it; only the LF had issues.

Since I'm caging the car now the weight etc will all change so I'm going to have to re-set the car. I may install camber blocks to push the LCA out even further, but then shim the upper A-arm to get the desired camber. That way I can add in more at the track if I need to.

If I'd had more time I would have possibly tried more rear bar, but the car felt good enough to win and I didn't want to waste a session trying something different. I haven't run the 255/aero setup enough to start to changing setups. Plus I was instructing and the weather was crazy so I didn't have a ton of free time. VIR's paddock is gravel and it was 38 degrees so I didn't feel like rolling around in cold gravely mud

Once I slowed my entry into T1 and Rollercoaster I was ok, but it can be better and I will tweak more when I get it out at Road Atlanta again in June.

[NZGTRA17]

Originally Posted by Cobra4B

I don't own a pyrometer yet. Plus, my camber is fixed in place with solid blocks so I can't change it unless I put a new block in. I can decrease it by shimming out the upper A-arm though. Right now I'm running 2.7 in th LF and about 2.6 in the RF as of my last allignment.

I'm not sure more camber will help... I think it's a function of running a 255/35 tire on a 10.5" wheel with a 2900lb car on top of it; only the LF had issues.

Since I'm caging the car now the weight etc will all change so I'm going to have to re-set the car. I may install camber blocks to push the LCA out even further, but then shim the upper A-arm to get the desired camber. That way I can add in more at the track if I need to.

If I'd had more time I would have possibly tried more rear bar, but the car felt good enough to win and I didn't want to waste a session trying something different. I haven't run the 255/aero setup enough to start to changing setups. Plus I was instructing and the weather was crazy so I didn't have a ton of free time. VIR's paddock is gravel and it was 38 degrees so I didn't feel like rolling around in cold gravely mud

Once I slowed my entry into T1 and Rollercoaster I was ok, but it can be better and I will tweak more when I get it out at Road Atlanta again in June.

Yup, running a 255 on a 10.5 rim may well be part of the problem especially with little sidewall to compensate. Probably about 1" to much rim width.

[Cobra4B]

Normally yes... but lets just say a stack of 255/35/18 Hoosiers is taller than a stack of 275/35/18s.... it's a "special" tire.

[NZGTRA17]

Originally Posted by Cobra4B

Normally yes... but lets just say a stack of 255/35/18 Hoosiers is taller than a stack of 275/35/18s.... it's a "special" tire.

Yes, saw that from specs on Hoosier site. I note they quote the measured rim as a 9" though Brian and max rim size as 10". So granted 10.5" is not far from max but wonder how the carcass actually deforms when taken out to 10.5".

We have seen some cording issues on tyres over here when the tyre is blown out onto the rim.

I have run Hoosiers for years (unitl I got the Panoz) and never had cording issues but have seen plenty that have with them. Always came down to settings and pressures.

Cant argue with the times they are producing on your car though so all good.